U.S. patent number 9,409,241 [Application Number 13/714,024] was granted by the patent office on 2016-08-09 for cutting tool and replaceable cutting head having spiral driven surfaces therefor.
This patent grant is currently assigned to Iscar, Ltd.. The grantee listed for this patent is Iscar, Ltd.. Invention is credited to Gil Hecht.
United States Patent |
9,409,241 |
Hecht |
August 9, 2016 |
Cutting tool and replaceable cutting head having spiral driven
surfaces therefor
Abstract
A replaceable cutting head includes a forward cutting portion
and a rearward mounting portion. The mounting portion includes a
male coupling member that protrudes rearwardly from a base surface.
The male coupling member includes three circumferentially spaced
apart head fixation members, where each head fixation member has a
head peripheral surface that spirals inwardly in a direction
against the direction of rotation and diverges. A tool holder
includes a female coupling member extends rearwardly from a holder
forward surface. The female coupling member includes three
circumferentially spaced apart holder fixation members, where each
holder fixation member has a holder peripheral surface that
diverges rearwardly. When a cutting tool, which includes said
cutting head and tool holder, is in a locked position, the male
coupling member of the replaceable cutting head is removably
retained within the female coupling member of the tool holder by
means of a self-lock mechanism.
Inventors: |
Hecht; Gil (Nahariya,
IL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Iscar, Ltd. |
Tefen |
N/A |
IL |
|
|
Assignee: |
Iscar, Ltd. (Tefen,
IL)
|
Family
ID: |
49885337 |
Appl.
No.: |
13/714,024 |
Filed: |
December 13, 2012 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140169892 A1 |
Jun 19, 2014 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23C
5/006 (20130101); B23C 5/22 (20130101); B23C
5/1009 (20130101); B23B 31/113 (20130101); B23C
5/10 (20130101); B23B 31/005 (20130101); Y10T
407/23 (20150115); B23C 2210/02 (20130101); B23C
2210/03 (20130101); Y10T 407/1924 (20150115); B23B
2231/0204 (20130101); B23C 2240/04 (20130101); Y10T
407/22 (20150115) |
Current International
Class: |
B23B
51/02 (20060101); B23B 31/00 (20060101); B23C
5/22 (20060101); B23C 5/00 (20060101); B23B
31/113 (20060101); B23C 5/10 (20060101); B23B
31/10 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
International Search Report dated Mar. 5, 2014 issued in PCT
counterpart application (no. PCT/IL2013/050983). cited by
applicant.
|
Primary Examiner: Fridie, Jr.; Will
Attorney, Agent or Firm: Womble Carlyle
Claims
What is claimed is:
1. A replaceable cutting head (22), for rotary cutting operations,
having a head longitudinal axis (A) around which the replaceable
cutting head (22) rotates in a direction of rotation (R), the head
longitudinal axis (A) extending in a forward (D.sub.F) to rearward
direction (D.sub.R), comprising: a forward portion forming a
cutting portion (26) and a rearward portion forming a mounting
portion (28); the cutting portion (26) comprising: a plurality of
cutting members (30) extending radially with respect to the head
longitudinal axis (A); and the mounting portion (28) comprising a
male coupling member (40) protruding rearwardly from a base surface
(42), the base surface (42) extending transversely with respect to
the head longitudinal axis (A), and defining a boundary between the
cutting portion (26) and the mounting portion (28), the male
coupling member (40) comprising: three circumferentially spaced
apart head fixation members (44), each head fixation member (44)
comprising a head peripheral surface (46) diverging rearwardly with
respect to the head longitudinal axis (A), wherein: in each cross
section of the male coupling member (40) taken in a plane through
the head peripheral surface (46) and perpendicular to the head
longitudinal axis (A), a first end point (PE1) on any head
peripheral surface (46) is closer to the head longitudinal axis (A)
than a second end point (PE2) on the same head peripheral surface
(46), the second end point (PE2) being circumferentially disposed
further in the direction of rotation (R) relative to the first end
point (PE1).
2. The replaceable cutting head (22) according to claim 1, wherein
a first angle .alpha. is formed between the head longitudinal axis
(A) and a line (T) tangential to any point on each head peripheral
surface (46), wherein the first angle .alpha. is in the range of
35.degree..ltoreq..alpha..ltoreq.55.degree..
3. The replaceable cutting head (22) according to claim 2, wherein
the first angle (.alpha.) is a 45.degree. angle.
4. The replaceable cutting head (22) according to claim 1, wherein
in each cross section of the male coupling member (40) taken in a
plane through the head peripheral surface (46) and perpendicular to
the head longitudinal axis (A), each head peripheral surface (46)
lies on a spiral (S), having a spiral center (S.sub.C), each head
peripheral surface (46) forming a spiral portion (SP).
5. The replaceable cutting head (22) according to claim 4, wherein
the two end points (PE1, PE2) of each spiral portion (SP) subtend a
peripheral surface angle .beta. relative to the spiral center
(S.sub.C); wherein the peripheral surface angle .beta. is in the
range of 30.degree..ltoreq..beta..ltoreq.60.degree..
6. The replaceable cutting head (22) according to claim 4, wherein
each spiral center (S.sub.C) is coincident with the head
longitudinal axis (A).
7. The replaceable cutting head (22) according to claim 4, wherein
each spiral (S) is an Archimedean spiral.
8. The replaceable cutting head (22) according to claim 7, wherein
the pitch angle (.delta.) of each spiral portion (SP) is less than
30.degree..
9. The replaceable cutting head (22) according to claim 1, wherein
the head peripheral surfaces (46) serve as spiral driven surfaces
applying torque transmission to the replaceable cutting head (22);
and the cutting portion (26) is devoid of a surface facing against
the direction of rotation (R) that serves as a driven surface for
applying torque transmission to the replaceable cutting head
(22).
10. The replaceable cutting head (22) according to claim 1, wherein
the head peripheral surfaces (46) serve as spiral driven surfaces
applying torque transmission to the replaceable cutting head (22);
and the mounting portion (28) is devoid of a surface facing against
the direction of rotation (R) that serves as a driven surface
applying torque transmission to the replaceable cutting head
(22).
11. The replaceable cutting head (22) according to claim 1, wherein
the male coupling member (40) is devoid of a resilience slit.
12. The replaceable cutting head (22) according to claim 1, wherein
the base surface (42) is perpendicular to the head longitudinal
axis (A).
13. The replaceable cutting head (22) according to claim 1, wherein
in an end view perpendicular to the head longitudinal axis (A), an
imaginary cutting portion circle (C.sub.CP) circumscribing the
cutting portion (26) has a maximum cutting portion diameter
(D.sub.CP); and the maximum cutting portion diameter (D.sub.CP) is
greater than or equal to 25 mm.
14. The replaceable cutting head (22) according to claim 1, wherein
an imaginary base surface circle (C.sub.BS) circumscribing a
largest dimension of the base surface (42), taken perpendicular to
the head longitudinal axis (A), has a maximum base surface diameter
(D.sub.BS); an imaginary male coupling member circle (C.sub.MCM)
circumscribing a largest dimension of the male coupling member
(40), taken perpendicular to the head longitudinal axis (A), has a
maximum male coupling member diameter (D.sub.MCM); and the maximum
base surface diameter (D.sub.BS) is at least one and a half times
as large as the maximum male coupling member diameter
(D.sub.MCM).
15. The replaceable cutting head (22) according to claim 1,
wherein, measured in the forward direction (D.sub.F) along the head
longitudinal axis (A) from the base surface (42), the cutting
portion (26) has a maximum cutting portion length (L.sub.CP),
measured in the rearward direction (D.sub.R) along the head
longitudinal axis (A) from the base surface (42), the mounting
portion (28) has a maximum mounting portion length (L.sub.MP); and
the maximum cutting portion length (L.sub.CP) is at least two and a
half times greater than the maximum mounting portion length
(L.sub.MP).
16. The replaceable cutting head (22) according to claim 1,
wherein, measured in the rearward direction (D.sub.F) along the
head longitudinal axis (A) from the base surface (42), the mounting
portion (28) has a maximum mounting portion length (L.sub.MP); an
imaginary base surface circle (C.sub.BS) circumscribing a largest
dimension of the base surface (42), taken perpendicular to the head
longitudinal axis (A), has a maximum base surface diameter
(D.sub.BS); and the maximum base surface diameter (D.sub.BS) is at
least three times greater than the maximum mounting portion length
(L.sub.MP).
17. The replaceable cutting head (22) according to claim 1, wherein
the male coupling member (40) exhibits 3-fold rotational symmetry
about the head longitudinal axis (A).
18. The replaceable cutting head (22) according to claim 1,
comprising a unitary integral one-piece construction.
19. The replaceable cutting head (22) according to claim 1, wherein
each head peripheral surface (46) lies on a portion of the curved
surface of an associated imaginary irregular cone, the cone having
a spiral-shaped base surface.
20. The replaceable cutting head (22) according to claim 1, wherein
the male coupling member (40) further comprises a rear surface
(48), the rear surface (48) intersecting the rearmost portion of
each head fixation member (44).
21. The replaceable cutting head (22) according to claim 20,
wherein the rear surface (48) is perpendicular with respect to the
head longitudinal axis (A).
22. The replaceable cutting head (22) according to claim 20,
wherein each head fixation member (44) further comprises a
chamfered surface (50), extending between the rear surface (48) and
each head peripheral surface (46), and converging rearwardly with
respect to the head longitudinal axis (A).
23. The replaceable cutting head (22) according to claim 20,
wherein each head fixation member (44) further comprises a concave
surface (66), extending between the base surface (42) and each head
peripheral surface (46).
24. A cutting tool (20) comprising: a replaceable cutting head (22)
in accordance with claim 1; and a tool holder (24), having a holder
longitudinal axis (C) extending in the forward (D.sub.F) to
rearward direction (D.sub.R), comprising a female coupling member
(52) extending rearwardly from a holder forward surface (54), the
holder forward surface (54) extending transversely with respect to
the holder longitudinal axis (C), the female coupling member (52)
comprising: three circumferentially spaced apart holder fixation
members (56), each holder fixation member (56) comprising a
recessed holder peripheral surface (58) diverging rearwardly with
respect to the holder longitudinal axis (C); and a holder rear
surface (60) extending transversely with respect to the holder
longitudinal axis (C) and intersecting each holder fixation member
(56); wherein the male coupling member (40) further comprises a
rear surface (48), the rear surface (48) intersecting the rearmost
portion of each head fixation member (44); and the replaceable
cutting head (22) is rotatable between a released position and a
locked position, wherein in the locked position: the male coupling
member (40) is removably retained in the female coupling member
(52); each of the head peripheral surfaces (46) abuts a
corresponding holder peripheral surface (58); the base surface (42)
abuts the holder forward surface (54); and the rear surface (48) is
spaced apart from the holder rear surface (60).
25. The cutting tool (20) according to claim 24, wherein the tool
holder (24) further comprises a holder shank surface (62) extending
rearwardly from the holder forward surface (54); the female
coupling member (52) opens out to the holder shank surface (62) at
three circumferentially spaced apart holder flute surfaces (64);
and the holder forward surface (54) comprises three spaced apart
portions.
26. The cutting tool (20) according to claim 24, wherein each
holder peripheral surface (58) spirals inwardly in a direction
against the direction of rotation (R).
27. The cutting tool (20) according to claim 24, wherein the head
longitudinal axis (A) is coaxial with the holder longitudinal axis
(C).
28. The cutting tool (20) according to claim 24, wherein the
peripheral portion of the holder forward surface (54) comprises a
raised surface (68).
29. A tool holder (24) having a longitudinal axis (C) extending in
a forward (D.sub.F) to a rearward direction (D.sub.R) and a
direction of rotation (R) about the longitudinal axis (C), the tool
holder comprising: a female coupling member (52) extending
rearwardly from a holder forward surface (54), the holder forward
surface (54) extending transversely with respect to the holder
longitudinal axis (C), the female coupling member (52) comprising:
three circumferentially spaced apart holder fixation members (56),
each holder fixation member (56) comprising a recessed holder
peripheral surface (58) diverging rearwardly with respect to the
holder longitudinal axis (C), wherein: in each cross-section of the
female coupling member (52) taken in a plane through the holder
peripheral surfaces (58) and perpendicular to the holder
longitudinal axis (C), a first female end point (FPE1) on a given
holder peripheral surface (58) is closer to the holder longitudinal
axis (C) than a second female end point (FPE2) on the same holder
peripheral surface (58), the second female end point (FPE2) being
circumferentially disposed further in the direction of rotation (R)
relative to the first female end point (FPE1); and each holder
peripheral surface (58) is formed as an undercut of a corresponding
holder fixation member (56) and hidden from view in a front view of
the tool holder (24) along the longitudinal axis (C); and a holder
rear surface (60) extending transversely with respect to the holder
longitudinal axis (C) and intersecting each holder fixation member
(56).
Description
FIELD OF THE INVENTION
The subject matter of the present application relates to cutting
tools of the type in which a cutting head, having a male coupling
member, is removably retained in a female coupling member, of a
tool holder, by means of a self-locking mechanism.
BACKGROUND OF THE INVENTION
Cutting tools can be provided with a coupling mechanism for
securely retaining a replaceable cutting head within a tool
holder.
The replaceable cutting head can include a male coupling member and
the tool holder can include a female coupling member.
In some such cutting tools, the male coupling member is an external
thread and the female coupling member is an internal thread. An
example of such a cutting tool is disclosed in, for example, U.S.
Pat. No. 6,494,648.
In other such cutting tools the cutting tool can include matching
radially extending surfaces on the replaceable cutting head and the
tool holder for applying a torque force from the tool holder to the
replaceable cutting head. Examples of such cutting tools are
disclosed in U.S. Pat. No. 7,407,350, WO 2011/021275 and US
2012/0155978.
In still other such cutting tools the cutting tool can be devoid of
said matching radially extending surfaces on the replaceable
cutting head and the tool holder. An Example of such a cutting tool
is disclosed in, for example, U.S. Pat. No. 6,276,879.
It is an object of the subject matter of the present application to
provide a cutting tool having an improved means of coupling a
replaceable cutting head in a tool holder.
It is a further object of the subject matter of the present
application to provide a cutting tool having coupling mechanism
between a replaceable cutting head and a tool holder with an
improved positioning of the replaceable cutting head with respect
to the tool holder when in a locked position.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the subject matter of the
present application there is provided a replaceable cutting head,
for rotary cutting operations, having a head longitudinal axis
around which the replaceable cutting head rotates in a direction of
rotation, the head longitudinal axis extending in a forward to
rearward direction, comprising:
a forward portion forming a cutting portion and a rearward portion
forming a mounting portion;
the cutting portion comprising: a plurality of cutting members
extending radially with respect to the head longitudinal axis;
and
the mounting portion comprising a male coupling member protruding
rearwardly from a base surface, the base surface extending
transversely with respect to the head longitudinal axis, and
defining a boundary between the cutting portion and the mounting
portion, the male coupling member comprising:
three circumferentially spaced apart head fixation members, each
head fixation member comprising a head peripheral surface spiraling
inwardly in a direction against the direction of rotation and
diverging rearwardly with respect to the head longitudinal
axis.
In accordance with a further aspect of the subject matter of the
present application, there is also provided a cutting tool
comprising:
a replaceable cutting head; and
a tool holder, having a holder longitudinal axis extending in the
forward to rearward direction, comprising a female coupling member
extending rearwardly from a holder forward surface, the holder
forward surface extending transversely with respect to the holder
longitudinal axis, the female coupling member comprising: three
circumferentially spaced apart holder fixation members, each holder
fixation member comprising a recessed holder peripheral surface
diverging rearwardly with respect to the holder longitudinal axis;
and a holder rear surface extending transversely with respect to
the holder longitudinal axis and intersecting each holder fixation
member; wherein
the male coupling member further comprises a rear surface, the rear
surface intersecting the rearmost portion of each head fixation
member; and
the replaceable cutting head is rotatable between a released
position and a locked position, wherein in the locked position: the
male coupling member is removably retained in the female coupling
member; each of the head peripheral surfaces abuts a corresponding
holder peripheral surface; the base surface abuts the holder
forward surface; and the rear surface is spaced apart from the
holder rear surface.
In accordance with a yet further aspect of the subject matter of
the present application, there is also provided a tool holder
having a longitudinal axis extending in a forward to a rearward
direction and a direction of rotation about the longitudinal axis,
the tool holder comprising:
a female coupling member extending rearwardly from a holder forward
surface, the holder forward surface extending transversely with
respect to the holder longitudinal axis, the female coupling member
comprising: three circumferentially spaced apart holder fixation
members, each holder fixation member comprising a recessed holder
peripheral surface diverging rearwardly with respect to the holder
longitudinal axis, wherein: each holder peripheral surface spirals
inwardly in a direction against the direction of rotation; and each
holder peripheral surface is formed as an undercut of a
corresponding holder fixation member and hidden from view in a
front view of the tool holder along the longitudinal axis; and a
holder rear surface extending transversely with respect to the
holder longitudinal axis and intersecting each holder fixation
member.
It is understood that the above-said is a summary, and that
features described hereinafter may be applicable in any combination
to the subject matter of the present application, for example, any
of the following features may be applicable to the replaceable
cutting head or the cutting tool: A. A first angle .alpha. can be
formed between the head longitudinal axis and a line tangential to
any point on each head peripheral surface, wherein the first angle
is in the range of 35.degree..ltoreq..alpha..ltoreq.55.degree.. B.
The first angle can be a 45.degree. angle. C. In each cross section
of the male coupling member taken in a plane through the head
peripheral surface and perpendicular to the head longitudinal axis,
each head peripheral surface can lie on a spiral, having a spiral
center, each head peripheral surface can form a spiral portion. D.
The two end points of each spiral portion can subtend a peripheral
surface angle .beta. relative to the spiral center, wherein the
peripheral surface angle .beta. can be in the range of
30.degree..ltoreq..beta..ltoreq.60.degree.. E. Each spiral center
can be coincident with the head longitudinal axis. F. Each spiral
can be an Archimedean spiral. G. The pitch angle of each spiral
portion can be less than 30.degree.. H. The head peripheral
surfaces can serve as spiral driven surfaces applying torque
transmission to the replaceable cutting head. The cutting portion
can be devoid of a surface facing against the direction of rotation
that can serve as a driven surface for applying torque transmission
to the replaceable cutting head. I. The head peripheral surfaces
can serve as spiral driven surfaces applying torque transmission to
the replaceable cutting head. The mounting portion can be devoid of
a surface facing against the direction of rotation that can serve
as a driven surface applying torque transmission to the replaceable
cutting head. J. The male coupling member can be devoid of a
resilience slit. K. The base surface can be perpendicular to the
head longitudinal axis. L. In an end view perpendicular to the head
longitudinal axis, an imaginary cutting portion circle
circumscribes the cutting portion has a maximum cutting portion
diameter. The maximum cutting portion diameter can be greater than
or equal to 25 mm. M. An imaginary base surface circle
circumscribing a largest dimension of the base surface, taken
perpendicular to the head longitudinal axis, has a maximum base
surface diameter. An imaginary male coupling member circle
circumscribing a largest dimension of the male coupling member,
taken perpendicular to the head longitudinal axis, has a maximum
male coupling member diameter and the maximum base surface diameter
can be at least one and a half times as large as the maximum male
coupling member diameter. N. Measured in the forward direction
along the head longitudinal axis from the base surface, the cutting
portion has a maximum cutting portion length. Measured in the
rearward direction along the head longitudinal axis from the base
surface, the mounting portion has a maximum mounting portion
length. The maximum cutting portion length can be at least two and
a half times greater than the maximum mounting portion length. O.
Measured in the rearward direction along the head longitudinal axis
from the base surface, the mounting portion has a maximum mounting
portion length. An imaginary base surface circle circumscribing a
largest dimension of the base surface, taken perpendicular to the
head longitudinal axis, has a maximum base surface diameter. The
maximum base surface diameter can be at least three times greater
than the maximum mounting portion length. P. The male coupling
member can exhibit 3-fold rotational symmetry about the head
longitudinal axis. Q. The replaceable cutting head comprise a
unitary integral one-piece construction. R. Each head peripheral
surface can lie on a portion of the curved surface of an associated
imaginary irregular cone. The cone can have a spiral-shaped base
surface. S. The male coupling member can further comprise a rear
surface. The rear surface can intersect the rearmost portion of
each head fixation member. T. The rear surface can be perpendicular
with respect to the head longitudinal axis. U. Each head fixation
member can further include a chamfered surface, each chamfered
surface can extend between its respective head peripheral surface
and the rear surface and can converge rearwardly with respect to
the head longitudinal axis. V. Each head fixation member can
further include a concave surface, extending between the base
surface and each head peripheral surface. W. The tool holder can
further comprise a holder shank surface that can extend rearwardly
from the holder forward surface. The female coupling member can
open out to the holder shank surface at three circumferentially
spaced apart holder flute surfaces. The holder forward surface
comprises three spaced apart portions. X. Each holder peripheral
surface can spiral inwardly in a direction against the direction of
rotation. Y. The head longitudinal axis can be coaxial with the
holder longitudinal axis. Z. The peripheral portion of the holder
forward surface can include a raised surface.
BRIEF DESCRIPTION OF THE FIGURES
For a better understanding of the present application and to show
how the same may be carried out in practice, reference will now be
made to the accompanying drawings, in which:
FIG. 1 is a front perspective view of a cutting tool;
FIG. 2 is an exploded rear perspective view of the cutting tool
shown in FIG. 1;
FIG. 3 is a rear perspective view of a replaceable cutting head
shown in FIGS. 1 and 2;
FIG. 4 is a front perspective view of the replaceable cutting head
shown in FIG. 3;
FIG. 5 is a front view of the replaceable cutting head shown in
FIG. 3;
FIG. 6 is a side view of the replaceable cutting head shown in FIG.
3;
FIG. 7 is a rear view of the replaceable cutting head in FIG.
3;
FIG. 8 is a side view of a male coupling member shown in FIG.
6;
FIG. 9 is a cross section view taken along line IX-IX shown in FIG.
8;
FIG. 10 is a front perspective of a tool holder shown in FIGS. 1
and 2;
FIG. 11 is a front view of the tool holder shown in FIG. 10;
FIG. 12 is a side view of the tool holder shown in FIGS. 10 and
11;
FIG. 13 is a cross section view taken along line XIIV-XIIV shown in
FIG. 12;
FIG. 14 is a side view of the cutting tool shown in FIGS. 1 and
2;
FIG. 15 is a cross section view taken along line XV-XV shown in
FIG. 14 when the cutting tool is in a released position; and
FIG. 16 is a cross section view taken along line XV-XV shown in
FIG. 14 when the cutting tool is in a locked position.
It will be appreciated that for simplicity and clarity of
illustration, elements shown in the figures have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements may be exaggerated relative to other elements for clarity,
or several physical components may be included in one functional
block or element. Where considered appropriate, reference numerals
may be repeated among the figures to indicate corresponding or
analogous elements.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, various aspects of the subject matter
of the present application will be described. For purposes of
explanation, specific configurations and details are set forth in
sufficient detail to provide a thorough understanding of the
subject matter of the present application. However, it will also be
apparent to one skilled in the art that the subject matter of the
present application can be practiced without the specific
configurations and details presented herein.
Attention is first drawn to FIGS. 1 and 2 showing a cutting tool 20
of the type used for milling operations, in particular end milling,
in accordance with embodiments of the subject matter of the present
application. The cutting tool 20 has a replaceable cutting head 22
that has a head longitudinal axis A, around which the replaceable
cutting head 22 rotates in a direction of rotation R. The
replaceable cutting head 22 can be typically made from cemented
carbide. The head longitudinal axis A extends in a forward D.sub.F
to rearward direction D.sub.R. The cutting tool 20 also has a tool
holder 24. The tool holder 24 can be typically made from steel. The
replaceable cutting head 22 can be removably retained in the tool
holder 24 by means of a coupling mechanism. Such a coupling
mechanism could possibly be advantageous for other types of rotary
cutting operations than those stated hereinabove, such as, for
example, slotting or grooving.
It should be appreciated that use of the terms "forward" and
"rearward" throughout the description and claims refer to a
relative position in a direction of the head longitudinal axis A
towards the left and right, respectively, in FIGS. 6, 8, 12 and
14.
Reference is now made to FIGS. 3 to 7. The replaceable cutting head
22 has a forward portion that forms a cutting portion 26 and a
rearward portion that forms a mounting portion 28. In accordance
with some embodiments of the subject matter of the present
application the replaceable cutting head 22 can be formed from a
unitary integral one-piece construction. This provides an advantage
in that the replaceable cutting head 22 has no detachable cutting
inserts (not shown). Such detachable cutting inserts can be
replaced periodically and this can be a time consuming procedure.
There is also a possibility that threaded screws (not shown), for
example, which can be used to releasably retain the detachable
cutting inserts to the replaceable cutting head 22 can be mislaid
and/or lost during the replacement operation.
As shown in FIGS. 4 and 5, the cutting portion 26 includes a
plurality of cutting members 30 that extend radially with respect
to the head longitudinal axis A. In accordance with some
embodiments of the subject matter of the present application, each
cutting member 30 can include a relief surface 32, a rake surface
34 and a cutting edge 36, at the intersection thereof. The cutting
edge 36 can extend in a direction generally parallel to the head
longitudinal axis A. The relief surface 32 can be located
circumferentially rearward of the cutting edge 36 and the rake
surface 34 can be located circumferentially forward of the cutting
edge 36, both in respect to the direction of rotation R. The
orientation of the cutting edge 36 with respect to the direction of
rotation R allows metal cutting operations to be performed. Each
cutting member 30 can include a head flute surface 38 for
evacuating chips (not shown) that are produced during the cutting
operation.
In accordance with some embodiments of the subject matter of the
present application, the cutting portion 26 can be devoid of a
surface that faces against the direction of rotation R that serves
as a driven surface for applying torque transmission to the
replaceable cutting head 22.
Referring now to FIG. 5, in an end view perpendicular to the head
longitudinal axis A, an imaginary cutting portion circle C.sub.CP
that circumscribes the cutting portion 26 has a maximum cutting
portion diameter D.sub.CP. In this non-limiting example, the
maximum cutting portion diameter D.sub.CP can be greater than or
equal to 25 mm. This is particularly applicable for a replaceable
cutting head 22 used for a milling operation. In another
non-limiting example, the maximum cutting portion diameter D.sub.CP
can be less than 25 mm.
Making reference now to FIGS. 3 and 6, the mounting portion 28
includes a male coupling member 40 that protrudes rearwardly from a
base surface 42. The base surface 42 extends transversely with
respect to the head longitudinal axis A and defines a boundary
between the cutting portion 26 and the mounting portion 28. That is
to say, the cutting portion 26 is formed forward of the base
surface 42 and the mounting portion 28 is formed rearward of the
base surface 42. In accordance with some embodiments of the subject
matter of the present application the male coupling member can be
rigid. The base surface 42 can be perpendicular to the head
longitudinal axis A. The base surface 42 is intended to abut a
corresponding surface on the tool holder 24 when the cutting tool
20 is in a locked position, as will be described hereinafter.
Reference is now made to FIGS. 3, 4, 7 and 9. The male coupling
member 40 includes three circumferentially spaced apart head
fixation members 44. Each head fixation member 44 includes a head
peripheral surface 46 that spirals inwardly in a direction against
the direction of rotation R. Stated differently, in each cross
section of the male coupling member 40 taken in a plane through the
head peripheral surface 46 and perpendicular to the head
longitudinal axis A, a first point P1 on any head peripheral
surface 46 is closer to the head longitudinal axis A than a second
point P2 on the same head peripheral surface 46, the second point
P2 being circumferentially disposed further in the direction of
rotation R relative to the first point P1. Each head peripheral
surface 46 diverges rearwardly with respect to the head
longitudinal axis A. Stated differently, each head peripheral
surface 46 generally faces in the forward direction so that the
male coupling member 40 has a general dove-tail shape in which the
head fixation members 44 extend radially from a central portion of
the male coupling member 40.
It should be appreciated that use of the terms "inward" and
"outward" throughout the description and claims refer to a relative
position in a radial direction in relation to the head longitudinal
axis A and/or holder longitudinal axis C inwardly and outwardly,
respectively, in FIGS. 5, 7, 9, 11, 13, 15 and 16.
By virtue of the configuration of the male coupling member 40 an
improved coupling mechanism is provided where each head peripheral
surface 46 is designed to abut a corresponding surface on the tool
holder 24 when the cutting tool 20 is in a locked position, as will
be described hereinafter, in order to provide a well-constrained
coupling of the replaceable cutting head 22 and the tool holder 24.
It is pointed out that a male coupling member 40 having exactly two
male fixation members 44 provides a coupling where the replaceable
cutting head 22 is under-constrained.
As shown in FIG. 8, in accordance with some embodiments of the
subject matter of the present application a first angle .alpha. is
formed between the head longitudinal axis A and a line T tangential
to any point on each head peripheral surface 46. The first angle
.alpha. can be greater than or equal to 35.degree. and less than or
equal to 55.degree.. In particular, the first angle .alpha. can be
constant and have a value of 45.degree..
In accordance with some embodiments of the subject matter of the
present application each head peripheral surface 46 can lie on a
portion of the curved surface of an associated imaginary irregular
cone, where the cone has a spiral-shaped base surface (not
shown).
Referring now to FIG. 9, in accordance with some embodiments of the
subject matter of the present application, in each cross section of
the male coupling member 40 taken in a plane through the head
peripheral surface 46 and perpendicular to the head longitudinal
axis A, each head peripheral surface 46 can lie on a spiral S, that
has a spiral center S.sub.C. Each head peripheral surface 46 can
form a spiral portion SP. The two end points of each spiral portion
SP can form a first and second end point PE1 PE2, the first end
point PE1 being circumferentially rearward than the second end
point PE2 in respect to the direction of rotation R. The two end
points PE1, PE2 are the points furthest from each other on the same
spiral portion SP. It can be equivalently stated, since each spiral
portion SP lies on the head peripheral surface 46, that the first
and second end point PE1 PE2 are formed at the extremities of each
head peripheral surface 46, in each said cross section. The two end
points PE1, PE2 can subtend a peripheral surface angle .beta.
relative to the spiral center S.sub.C. The peripheral surface angle
.beta. can be greater than or equal to 30.degree. and less than or
equal to 60.degree.. Each spiral S can be an Archimedean spiral.
The pitch angle .delta. of each spiral portion SP can be less than
30.degree.. Each spiral center S.sub.C can be coincident with the
head longitudinal axis A. The pitch angle .delta. determines the
magnitude of the force that must be applied in order to self-lock
the replaceable cutting head 22 into the tool holder 24. It should
be appreciated that use of the terms "pitch angle" throughout the
description and claims refer the angle the spiral makes with
circles centered at the spiral center S.sub.C.
In accordance with some embodiments of the subject matter of the
present application the male coupling member 40 can further include
a rear surface 48. The rear surface 48 can intersect the rearmost
portion of each head fixation member 44. The rear surface 48 can be
perpendicular with respect to the head longitudinal axis A. As is
best shown in FIG. 8, each head fixation member 44 can further
include a chamfered surface 50. Each chamfered surface 50 can
extend between its respective head peripheral surface 46 and the
rear surface 48, and can converge rearwardly with respect to the
head longitudinal axis A. The chamfered surface 50 can have a
frusto-conical shape. The chamfered surface 50 is intended to guide
the male coupling member 40 into the correct position within a
corresponding female coupling member. As seen in FIG. 6, each head
fixation member 44 can further include a concave surface 66,
extending between the base surface 42 and each head peripheral
surface 46.
Making reference now to FIG. 7, in accordance with some embodiments
of the subject matter of the present application an imaginary base
surface circle C.sub.BS that circumscribes a largest dimension of
the base surface 42, taken perpendicular to the head longitudinal
axis A, can have a maximum base surface diameter D.sub.BS. An
imaginary male coupling member circle C.sub.MCM that circumscribes
a largest dimension of the male coupling member 40, taken
perpendicular to the head longitudinal axis A, can have a maximum
male coupling member diameter D.sub.MCM. The maximum base surface
diameter D.sub.BS can be at least one and a half times as large as
the maximum male coupling member diameter D.sub.MCM.
Making reference now to FIG. 6, in accordance with some embodiments
of the subject matter of the present application, measured in the
direction of the head longitudinal axis A, the cutting portion 26
has a maximum cutting portion length L.sub.CP and the mounting
portion 28 has a maximum mounting portion length L.sub.MP. The
maximum cutting portion length L.sub.CP is measured in the forward
direction D.sub.F from the base surface 42 to the forwardmost point
of the cutting head. The maximum mounting portion length L.sub.MP
is measured in the rearward direction D.sub.R from the base surface
42 to the rear surface 48. The maximum cutting portion length
L.sub.CP can be at least two and a half times greater than the
maximum mounting portion length L.sub.MP. This is particularly
applicable when the replaceable cutting head 22 is intended for a
milling operation. In another non-limiting example, the maximum
cutting portion length L.sub.CP can be less than two and a half
times greater than the maximum mounting portion length L.sub.MP.
This is particularly applicable when the replaceable cutting head
is intended for a slotting or grooving operation. The maximum base
surface diameter D.sub.BS can be at least three times greater than
the maximum mounting portion length L.sub.MP.
In accordance with some embodiments of the subject matter of the
present application, the head peripheral surfaces 46 can serve as
spiral driven surfaces applying torque transmission to the
replaceable cutting head 22. The mounting portion 28 can be devoid
of a surface that faces against the direction of rotation R that
serves as a driven surface for providing torque transmission to the
replaceable cutting head 22.
In accordance with some embodiments of the subject matter of the
present application the male coupling member 40 can be devoid of a
resilience slit. Referring now to FIG. 7, the male coupling member
40 can exhibit 3-fold rotational symmetry about the head
longitudinal axis A. In this non-limiting example, the number of
cutting members 30 can also be three. Also in this non-limiting
example, the replaceable cutting head 22 can exhibit 3-fold
rotational symmetry about the head longitudinal axis A.
Another aspect of the subject matter of the present application
includes the cutting tool 20 that has the replaceable cutting head
22 and the tool holder 24. The male coupling member 40 of the
replaceable cutting head 22 includes a rear surface 48. The rear
surface 48 intersects the rearmost portion of each head fixation
member 44. Referring now to FIGS. 10 to 12, the tool holder 24 has
a holder longitudinal axis C that extends in the forward D.sub.F to
rearward direction D.sub.R. The tool holder 24 includes a female
coupling member 52 that extends rearwardly from a holder forward
surface 54. The holder forward surface 54 extends transversely with
respect to the holder longitudinal axis C. The female coupling
member 52 includes three circumferentially spaced apart holder
fixation members 56. Each holder fixation member 56 includes a
recessed holder peripheral surface 58 that diverges rearwardly with
respect to the holder longitudinal axis C. Stated differently, each
recessed holder peripheral surface 58 generally faces in the
rearward direction D.sub.R. As seen from FIGS. 11 and 12, each
holder peripheral surface 58 is formed as an undercut of a
corresponding holder fixation member 56 and thus is hidden from
view in a front view of the tool holder 24 along the longitudinal
axis C. The female coupling member 52 includes a holder rear
surface 60 that extends transversely with respect to the holder
longitudinal axis C and that intersects each holder fixation member
56.
Referring now to FIG. 13, in accordance with some embodiments of
the subject matter of the present application, in each cross
section of the female coupling member 52 taken in a plane through
the holder peripheral surface 58 and perpendicular to the holder
longitudinal axis C, the two female end points on the same holder
peripheral surface 58 form a first and second female end point FPE1
FPE2, the first female end point FPE1 being circumferentially
rearward than the second female end point FPE2 in respect to the
direction of rotation R. The two female end points FPE1, FPE2 are
the points furthest from each other on the same holder peripheral
surface 58 in each cross section of the female coupling member 52
taken in a plane through the holder peripheral surface 58 and
perpendicular to the holder longitudinal axis C.
Referring now to FIGS. 15 and 16, the replaceable cutting head 20
is rotatable between a released position and a locked position. In
the locked position, the male coupling member 40 is removably
retained in the female coupling member 52. As best shown in FIGS.
14 and 16, each of the head peripheral surfaces 46 abuts a
corresponding holder peripheral surface 58. The base surface 42
abuts the holder forward surface 54. The rear surface 48 is spaced
apart from the holder rear surface 60.
Further in a locked position, in accordance with some embodiments
of the subject matter of the present application, in each cross
section of the cutting tool 40 perpendicular to the head
longitudinal axis A taken in a plane through the head peripheral
surface 46 and holder peripheral surface 58, each first end point
PE1 on the head peripheral surface 46 can be spaced apart from the
female first end point FPE1 on its associated holder peripheral
surface 58. Each second end point PE2 on the head peripheral
surface 46 can be adjacent to the second female end point FPE2 on
its associated holder peripheral surface 58. It should be
appreciated that use of the terms "associated" throughout the
description in respect to the head peripheral surfaces 46 and
holder peripheral surfaces 58 refer to the head peripheral surface
46 and the holder peripheral surface 58 that abut each other when
the cutting tool 20 is in the locked position.
In accordance with some embodiments of the subject matter of the
present application, the tool holder 24 can further include a
holder shank surface 62 that extends rearwardly from the holder
forward surface 54. In this non-limiting example, the female
coupling member 52 can open out to the holder shank surface 62 at
three circumferentially spaced apart holder flute surfaces 64. In
this case the holder forward surface 54 can be formed from three
spaced apart portions. In another non-limiting example the female
coupling member 52 cannot open out to the holder shank surface 62.
Stated differently the female coupling member 52 is closed. In this
case the holder forward surface 54 can be formed from a single
continuous portion.
As best seen in FIG. 13, in accordance with some embodiments of the
subject matter of the present application, each holder peripheral
surface 58 can spiral inwardly in a direction against the direction
of rotation R. The head longitudinal axis A can be coaxial with the
holder longitudinal axis C. The peripheral portion of the holder
forward surface 54 can include a raised surface 68. Stated
differently, the raised surface 68 protrudes in a forward direction
D.sub.F from the holder forward surface 54. The raised surface 68
is intended to ensure that the abutment of the base surface 42 with
the holder forward surface 54 occurs at a peripheral portion of the
holder forward surface 54 in order to provide a solid support
surface, and not, for example at an area close to the holder
longitudinal axis C.
Another aspect of the subject matter of the present application
includes a tool holder 24 as defined herein above. Each holder
peripheral surface 58 spirals inwardly in a direction against the
direction of rotation R. Thus, as seen in FIG. 13, in each
cross-section of the female coupling member 52 taken in a plane
through the holder peripheral surfaces 58 and perpendicular to the
holder longitudinal axis C, a first female end point FPE1 on a
given holder peripheral surface 58 is closer to the holder
longitudinal axis C than a second female end point FPE2 on the same
holder peripheral surface 58, the second female end point FPE2
being circumferentially disposed further in the direction of
rotation R relative to the first female end point FPE1.
Assembly of the cutting tool 20 is accomplished by performing the
following steps. The male coupling member 40 is inserted into the
female coupling member 52 such that each head fixation member 44 is
located axially forward and circumferentially between, each
adjacent pair of holder fixation members 56 (as best seen in FIG.
15). The replaceable cutting head 22 is then displaced rearwardly
until the base surface 42 initially comes into contact with the
holder forward surface 54. It should be noted that the head
fixation members 44 and the holder fixation members 56 are so
designed so that there is adequate space between each adjacent pair
of holder fixation members 56 to allow the placement of a head
fixation member 44. In this position the cutting tool 20 is in a
released position.
It is pointed out that, as seen in FIG. 15, in the released
position, in each cross section of the cutting tool 40
perpendicular to the head longitudinal axis A taken in a plane
through the head peripheral surface 46 and holder peripheral
surface 58, the distance of the first end point PE1 on each head
peripheral surface 46 to the head longitudinal axis A is less than
the distance of the corresponding second female end point FPE2 on
the associated holder peripheral surface 58 to the head
longitudinal axis A. By virtue of the spiral shape of the head
peripheral surface 46, the distance of the second end point PE2 on
each head peripheral surface 46 to the head longitudinal axis A is
more than the distance of the corresponding first female end point
FPE1 on an associated holder peripheral surface 58 to the head
longitudinal axis A.
The replaceable cutting head 22 is rotated in a direction against
the direction of rotation R, until each head peripheral surface 46
initially comes into contact with a corresponding respective holder
peripheral surface 58. Rotating the replaceable cutting head 22
further in a direction against the direction of rotation R pushes
on the holder peripheral surfaces 58, thereby forcing the
corresponding holder fixation members 56 to be elastically
displaced in a radially outwardly direction with respect to the
holder longitudinal axis C. This is due to the increasing radius of
the head peripheral surface 46. Consequently the holder forward
surface 54 is displaced axially forwardly until it firmly abuts the
base surface 42. The rear surface 48 is spaced apart from the
holder rear surface 60. In this locked position, a tight fit
between the replaceable cutting head 22 and the tool holder 24 is
accomplished. The coupling mechanism described herein above
provides a self-lock between the replaceable cutting head 22 and
the tool holder 24.
It should be noted that the value of the pitch angle .delta. as
described above determines the amount of rotational force required
to accomplish the locked position of the cutting tool 20. Stated
differently, as the pitch angle approaches 0.degree. less force is
required to rotate the replaceable cutting head 22 in the tool
holder 24. However, more rotational displacement (e.g. rotations
and/or partial rotations) of the replaceable cutting head 24 is
required to accomplish a self-lock. Alternatively, as the pitch
angle increases away from 0.degree. more force is required to
rotate the replaceable cutting head 22 in the tool holder 24.
Moreover, by virtue of the head peripheral surfaces 46 being
spiraling surfaces, the magnitude of the rotational force required
to accomplish the locked position increases gradually and
smoothly.
It should also be noted that a feature of subject matter of the
present application is that the male and female coupling members
40, 52 provide an improved coupling mechanism in particular for
large replaceable cutting heads 22, where the maximum cutting
portion diameter D.sub.CP can be greater than or equal to 25
mm.
The design of the replaceable cutting head 22 and the tool holder
24 according to the subject matter of the present application and,
particularly, the shape and orientation of the head peripheral
surfaces 46 and the holder peripheral surfaces 58, ensure that the
friction between these surfaces is sufficient to keep them in their
mutual abutment when the replaceable cutting 22 head and the tool
holder 24 are coupled together. This allows for a tight fit of the
replaceable cutting head 22 and the tool holder 24 in an accurately
established mutual axial and radial position. Consequently, the
replaceable cutting head 22 is accurately positioned and securely
retained in the tool holder 24 in a self-locking manner. It will be
understood from the foregoing that the head peripheral surfaces 46
are spiral driven surfaces applying torque transmission to the
replaceable cutting head 22.
Another feature of the subject matter of the present application is
that the design of the male coupling member 40 allows for the head
peripheral surface 46 to be ground.
Yet another feature of the subject matter of the present
application is that there is no requirement for a surface on the
cutting portion 26 or the mounting portion 28 that faces against
the direction of rotation R and that serves as a driven surface for
applying torque transmission to the replaceable cutting head
22.
Yet another feature of the subject matter of the present
application is that there is no requirement for a surface on the
tool holder 24 that faces the direction of rotation R that serves
as a driving surface for providing torque transmission to the
replaceable cutting head 22.
Yet another feature of the subject matter of the present
application is that the size of the mounting portion 28 is small in
relation to the size of mounting portions of other cutting tools
having a cutting portion of comparable size. Therefore, manufacture
of replaceable cutting heads 22, in accordance with the subject
matter of the present application, requires less material.
Although the subject matter of the present application has been
described to a certain degree of particularity, it should be
understood that various alterations and modifications could be made
without departing from the spirit or scope of the invention as
hereinafter claimed.
* * * * *